在实体框架中使用.include创建巨大的查询？
[英]using .include in entity framework create huge query?
问题描述
I wasn't expecting a generated query like this... 
我没想到像这样生成的查询......
let go back, if I keep one include, the query look good, it does a simple left join 放开，如果我保留一个包含，查询看起来不错，它会做一个简单的左连接
Query: 查询：
using (var db = new Context())
{
var data = db.MainTables.Include(x => x.LookupTables)
.Where(d => d.MainId == 10)
.FirstOrDefault();
}
SQL generated: SQL生成：
Opened connection at 2014-05-12 17:37:10 -04:00
SELECT
[Project1].[MainId] AS [MainId],
[Project1].[C1] AS [C1],
[Project1].[LookupId] AS [LookupId]
FROM ( SELECT
[Limit1].[MainId] AS [MainId],
[Extent2].[LookupId] AS [LookupId],
CASE WHEN ([Extent2].[MainId] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1]
FROM (SELECT TOP (1) [Extent1].[MainId] AS [MainId]
FROM [dbo].[MainTable] AS [Extent1]
WHERE 10 = [Extent1].[MainId] ) AS [Limit1]
LEFT OUTER JOIN [dbo].[MainTable_LookupTable] AS [Extent2] ON [Limit1].[MainId] = [Extent2].[MainId]
) AS [Project1]
ORDER BY [Project1].[MainId] ASC, [Project1].[C1] ASC
-- Executing at 2014-05-12 17:37:11 -04:00
-- Completed in 11 ms with result: SqlDataReader
Closed connection at 2014-05-12 17:37:11 -04:00
if i have more than one, the query get crazy like hell with UNION ALL... 如果我有一个以上，查询会像UNION ALL一样疯狂......
is that an expected behavior? 这是一种预期的行为吗？ if yes, is it possible to keep the behavior of one include while using more than one, simple left join for all of them? 如果是的话，是否可以保留一个包含的行为，同时为所有这些包含多个简单的左连接？
Model: 模型：
Query: 查询：
using (var db = new Context())
{
var data = db.MainTables.Include(x => x.LookupTables)
.Include(x => x.MainTable_MoreData)
.Include(x => x.MaintTable_DataLookup)
.Include(x => x.MainTable_EvenMoreData)
.Where(d => d.MainId == 10)
.FirstOrDefault()
}
SQL generated: SQL生成：
Opened connection at 2014-05-12 18:00:56 -04:00
SELECT
[UnionAll3].[C2] AS [C1],
[UnionAll3].[C3] AS [C2],
[UnionAll3].[C4] AS [C3],
[UnionAll3].[C5] AS [C4],
[UnionAll3].[C6] AS [C5],
[UnionAll3].[C7] AS [C6],
[UnionAll3].[C8] AS [C7],
[UnionAll3].[C9] AS [C8],
[UnionAll3].[C10] AS [C9],
[UnionAll3].[C11] AS [C10],
[UnionAll3].[C12] AS [C11],
[UnionAll3].[C13] AS [C12],
[UnionAll3].[C1] AS [C13],
[UnionAll3].[C14] AS [C14],
[UnionAll3].[C15] AS [C15],
[UnionAll3].[C16] AS [C16],
[UnionAll3].[C17] AS [C17],
[UnionAll3].[C18] AS [C18],
[UnionAll3].[C19] AS [C19],
[UnionAll3].[C20] AS [C20],
[UnionAll3].[C21] AS [C21],
[UnionAll3].[C22] AS [C22],
[UnionAll3].[C23] AS [C23],
[UnionAll3].[C24] AS [C24],
[UnionAll3].[C25] AS [C25],
[UnionAll3].[C26] AS [C26],
[UnionAll3].[C27] AS [C27],
[UnionAll3].[C28] AS [C28],
[UnionAll3].[C29] AS [C29],
[UnionAll3].[C30] AS [C30],
[UnionAll3].[C31] AS [C31],
[UnionAll3].[C32] AS [C32],
[UnionAll3].[C33] AS [C33],
[UnionAll3].[C34] AS [C34],
[UnionAll3].[C35] AS [C35],
[UnionAll3].[C36] AS [C36],
[UnionAll3].[C37] AS [C37],
[UnionAll3].[C38] AS [C38],
[UnionAll3].[C39] AS [C39],
[UnionAll3].[C40] AS [C40],
[UnionAll3].[C41] AS [C41],
[UnionAll3].[C42] AS [C42],
[UnionAll3].[C43] AS [C43],
[UnionAll3].[C44] AS [C44],
[UnionAll3].[C45] AS [C45],
[UnionAll3].[C46] AS [C46],
[UnionAll3].[C47] AS [C47],
[UnionAll3].[C48] AS [C48],
[UnionAll3].[C49] AS [C49],
[UnionAll3].[C50] AS [C50],
[UnionAll3].[C51] AS [C51]
FROM (SELECT
[UnionAll2].[C1] AS [C1],
[UnionAll2].[C2] AS [C2],
[UnionAll2].[C3] AS [C3],
[UnionAll2].[C4] AS [C4],
[UnionAll2].[C5] AS [C5],
[UnionAll2].[C6] AS [C6],
[UnionAll2].[C7] AS [C7],
[UnionAll2].[C8] AS [C8],
[UnionAll2].[C9] AS [C9],
[UnionAll2].[C10] AS [C10],
[UnionAll2].[C11] AS [C11],
[UnionAll2].[C12] AS [C12],
[UnionAll2].[C13] AS [C13],
[UnionAll2].[C14] AS [C14],
[UnionAll2].[C15] AS [C15],
[UnionAll2].[C16] AS [C16],
[UnionAll2].[C17] AS [C17],
[UnionAll2].[C18] AS [C18],
[UnionAll2].[C19] AS [C19],
[UnionAll2].[C20] AS [C20],
[UnionAll2].[C21] AS [C21],
[UnionAll2].[C22] AS [C22],
[UnionAll2].[C23] AS [C23],
[UnionAll2].[C24] AS [C24],
[UnionAll2].[C25] AS [C25],
[UnionAll2].[C26] AS [C26],
[UnionAll2].[C27] AS [C27],
[UnionAll2].[C28] AS [C28],
[UnionAll2].[C29] AS [C29],
[UnionAll2].[C30] AS [C30],
[UnionAll2].[C31] AS [C31],
[UnionAll2].[C32] AS [C32],
[UnionAll2].[C33] AS [C33],
[UnionAll2].[C34] AS [C34],
[UnionAll2].[C35] AS [C35],
[UnionAll2].[C36] AS [C36],
[UnionAll2].[C37] AS [C37],
[UnionAll2].[C38] AS [C38],
[UnionAll2].[C39] AS [C39],
[UnionAll2].[C40] AS [C40],
[UnionAll2].[C41] AS [C41],
[UnionAll2].[C42] AS [C42],
[UnionAll2].[C43] AS [C43],
[UnionAll2].[C44] AS [C44],
[UnionAll2].[C45] AS [C45],
[UnionAll2].[C46] AS [C46],
[UnionAll2].[C47] AS [C47],
[UnionAll2].[C48] AS [C48],
[UnionAll2].[C49] AS [C49],
[UnionAll2].[C50] AS [C50],
[UnionAll2].[C51] AS [C51]
FROM (SELECT
[UnionAll1].[C1] AS [C1],
[UnionAll1].[MainId] AS [C2],
[UnionAll1].[MainId1] AS [C3],
[UnionAll1].[Field1] AS [C4],
[UnionAll1].[Field11] AS [C5],
[UnionAll1].[Field12] AS [C6],
[UnionAll1].[Field13] AS [C7],
[UnionAll1].[Field14] AS [C8],
[UnionAll1].[Field15] AS [C9],
[UnionAll1].[Field16] AS [C10],
[UnionAll1].[Field17] AS [C11],
[UnionAll1].[Field18] AS [C12],
[UnionAll1].[Field19] AS [C13],
[UnionAll1].[LookupId] AS [C14],
[UnionAll1].[Field161] AS [C15],
[UnionAll1].[Field151] AS [C16],
[UnionAll1].[Field141] AS [C17],
[UnionAll1].[Field131] AS [C18],
[UnionAll1].[Field121] AS [C19],
[UnionAll1].[Field111] AS [C20],
[UnionAll1].[Field110] AS [C21],
[UnionAll1].[C2] AS [C22],
[UnionAll1].[C3] AS [C23],
[UnionAll1].[C4] AS [C24],
[UnionAll1].[C5] AS [C25],
[UnionAll1].[C6] AS [C26],
[UnionAll1].[C7] AS [C27],
[UnionAll1].[C8] AS [C28],
[UnionAll1].[C9] AS [C29],
[UnionAll1].[C10] AS [C30],
[UnionAll1].[C11] AS [C31],
[UnionAll1].[C12] AS [C32],
[UnionAll1].[C13] AS [C33],
[UnionAll1].[C14] AS [C34],
[UnionAll1].[C15] AS [C35],
[UnionAll1].[C16] AS [C36],
[UnionAll1].[C17] AS [C37],
[UnionAll1].[C18] AS [C38],
[UnionAll1].[C19] AS [C39],
[UnionAll1].[C20] AS [C40],
[UnionAll1].[C21] AS [C41],
[UnionAll1].[C22] AS [C42],
[UnionAll1].[C23] AS [C43],
[UnionAll1].[C24] AS [C44],
[UnionAll1].[C25] AS [C45],
[UnionAll1].[C26] AS [C46],
[UnionAll1].[C27] AS [C47],
[UnionAll1].[C28] AS [C48],
[UnionAll1].[C29] AS [C49],
[UnionAll1].[C30] AS [C50],
[UnionAll1].[C31] AS [C51]
FROM (SELECT
CASE WHEN ([Join1].[MainId] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1],
[Limit1].[MainId] AS [MainId],
[Limit1].[MainId] AS [MainId1],
[Limit1].[Field1] AS [Field1],
[Limit1].[Field11] AS [Field11],
[Limit1].[Field12] AS [Field12],
[Limit1].[Field13] AS [Field13],
[Limit1].[Field14] AS [Field14],
[Limit1].[Field15] AS [Field15],
[Limit1].[Field16] AS [Field16],
[Limit1].[Field17] AS [Field17],
[Limit1].[Field18] AS [Field18],
[Limit1].[Field19] AS [Field19],
[Join1].[LookupId1] AS [LookupId],
[Join1].[Field16] AS [Field161],
[Join1].[Field15] AS [Field151],
[Join1].[Field14] AS [Field141],
[Join1].[Field13] AS [Field131],
[Join1].[Field12] AS [Field121],
[Join1].[Field11] AS [Field111],
[Join1].[Field1] AS [Field110],
CAST(NULL AS int) AS [C2],
CAST(NULL AS int) AS [C3],
CAST(NULL AS varchar(1)) AS [C4],
CAST(NULL AS varchar(1)) AS [C5],
CAST(NULL AS varchar(1)) AS [C6],
CAST(NULL AS varchar(1)) AS [C7],
CAST(NULL AS varchar(1)) AS [C8],
CAST(NULL AS varchar(1)) AS [C9],
CAST(NULL AS varchar(1)) AS [C10],
CAST(NULL AS int) AS [C11],
CAST(NULL AS varchar(1)) AS [C12],
CAST(NULL AS varchar(1)) AS [C13],
CAST(NULL AS varchar(1)) AS [C14],
CAST(NULL AS varchar(1)) AS [C15],
CAST(NULL AS varchar(1)) AS [C16],
CAST(NULL AS varchar(1)) AS [C17],
CAST(NULL AS varchar(1)) AS [C18],
CAST(NULL AS int) AS [C19],
CAST(NULL AS int) AS [C20],
CAST(NULL AS int) AS [C21],
CAST(NULL AS varchar(1)) AS [C22],
CAST(NULL AS varchar(1)) AS [C23],
CAST(NULL AS varchar(1)) AS [C24],
CAST(NULL AS varchar(1)) AS [C25],
CAST(NULL AS varchar(1)) AS [C26],
CAST(NULL AS varchar(1)) AS [C27],
CAST(NULL AS varchar(1)) AS [C28],
CAST(NULL AS varchar(1)) AS [C29],
CAST(NULL AS varchar(1)) AS [C30],
CAST(NULL AS int) AS [C31]
FROM (SELECT TOP (1) [Extent1].[MainId] AS [MainId], [Extent1].[Field1] AS [Field1], [Extent1].[Field11] AS [Field11], [Extent1].[Field12] AS [Field12], [Extent1].[Field13] AS [Field13], [Extent1].[Field14] AS [Field14], [Extent1].[Field15] AS [Field15], [Extent1].[Field16] AS [Field16], [Extent1].[Field17] AS [Field17], [Extent1].[Field18] AS [Field18], [Extent1].[Field19] AS [Field19]
FROM [dbo].[MainTable] AS [Extent1]
WHERE 10 = [Extent1].[MainId] ) AS [Limit1]
LEFT OUTER JOIN (SELECT [Extent2].[MainId] AS [MainId], [Extent3].[LookupId] AS [LookupId1], [Extent3].[Field16] AS [Field16], [Extent3].[Field15] AS [Field15], [Extent3].[Field14] AS [Field14], [Extent3].[Field13] AS [Field13], [Extent3].[Field12] AS [Field12], [Extent3].[Field11] AS [Field11], [Extent3].[Field1] AS [Field1]
FROM [dbo].[MainTable_LookupTable] AS [Extent2]
INNER JOIN [dbo].[LookupTable] AS [Extent3] ON [Extent3].[LookupId] = [Extent2].[LookupId] ) AS [Join1] ON [Limit1].[MainId] = [Join1].[MainId]
UNION ALL
SELECT
2 AS [C1],
[Limit2].[MainId] AS [MainId],
[Limit2].[MainId] AS [MainId1],
[Limit2].[Field1] AS [Field1],
[Limit2].[Field11] AS [Field11],
[Limit2].[Field12] AS [Field12],
[Limit2].[Field13] AS [Field13],
[Limit2].[Field14] AS [Field14],
[Limit2].[Field15] AS [Field15],
[Limit2].[Field16] AS [Field16],
[Limit2].[Field17] AS [Field17],
[Limit2].[Field18] AS [Field18],
[Limit2].[Field19] AS [Field19],
CAST(NULL AS int) AS [C2],
CAST(NULL AS varchar(1)) AS [C3],
CAST(NULL AS varchar(1)) AS [C4],
CAST(NULL AS varchar(1)) AS [C5],
CAST(NULL AS varchar(1)) AS [C6],
CAST(NULL AS varchar(1)) AS [C7],
CAST(NULL AS varchar(1)) AS [C8],
CAST(NULL AS varchar(1)) AS [C9],
[Extent5].[DataId] AS [DataId],
[Extent5].[MainId] AS [MainId2],
[Extent5].[SomeData] AS [SomeData],
[Extent5].[Field1] AS [Field110],
[Extent5].[Field11] AS [Field111],
[Extent5].[Field12] AS [Field121],
[Extent5].[Field13] AS [Field131],
[Extent5].[Field14] AS [Field141],
[Extent5].[Field15] AS [Field151],
CAST(NULL AS int) AS [C10],
CAST(NULL AS varchar(1)) AS [C11],
CAST(NULL AS varchar(1)) AS [C12],
CAST(NULL AS varchar(1)) AS [C13],
CAST(NULL AS varchar(1)) AS [C14],
CAST(NULL AS varchar(1)) AS [C15],
CAST(NULL AS varchar(1)) AS [C16],
CAST(NULL AS varchar(1)) AS [C17],
CAST(NULL AS int) AS [C18],
CAST(NULL AS int) AS [C19],
CAST(NULL AS int) AS [C20],
CAST(NULL AS varchar(1)) AS [C21],
CAST(NULL AS varchar(1)) AS [C22],
CAST(NULL AS varchar(1)) AS [C23],
CAST(NULL AS varchar(1)) AS [C24],
CAST(NULL AS varchar(1)) AS [C25],
CAST(NULL AS varchar(1)) AS [C26],
CAST(NULL AS varchar(1)) AS [C27],
CAST(NULL AS varchar(1)) AS [C28],
CAST(NULL AS varchar(1)) AS [C29],
CAST(NULL AS int) AS [C30]
FROM (SELECT TOP (1) [Extent4].[MainId] AS [MainId], [Extent4].[Field1] AS [Field1], [Extent4].[Field11] AS [Field11], [Extent4].[Field12] AS [Field12], [Extent4].[Field13] AS [Field13], [Extent4].[Field14] AS [Field14], [Extent4].[Field15] AS [Field15], [Extent4].[Field16] AS [Field16], [Extent4].[Field17] AS [Field17], [Extent4].[Field18] AS [Field18], [Extent4].[Field19] AS [Field19]
FROM [dbo].[MainTable] AS [Extent4]
WHERE 10 = [Extent4].[MainId] ) AS [Limit2]
INNER JOIN [dbo].[MainTable_MoreData] AS [Extent5] ON [Limit2].[MainId] = [Extent5].[MainId]) AS [UnionAll1]
UNION ALL
SELECT
3 AS [C1],
[Limit3].[MainId] AS [MainId],
[Limit3].[MainId] AS [MainId1],
[Limit3].[Field1] AS [Field1],
[Limit3].[Field11] AS [Field11],
[Limit3].[Field12] AS [Field12],
[Limit3].[Field13] AS [Field13],
[Limit3].[Field14] AS [Field14],
[Limit3].[Field15] AS [Field15],
[Limit3].[Field16] AS [Field16],
[Limit3].[Field17] AS [Field17],
[Limit3].[Field18] AS [Field18],
[Limit3].[Field19] AS [Field19],
CAST(NULL AS int) AS [C2],
CAST(NULL AS varchar(1)) AS [C3],
CAST(NULL AS varchar(1)) AS [C4],
CAST(NULL AS varchar(1)) AS [C5],
CAST(NULL AS varchar(1)) AS [C6],
CAST(NULL AS varchar(1)) AS [C7],
CAST(NULL AS varchar(1)) AS [C8],
CAST(NULL AS varchar(1)) AS [C9],
CAST(NULL AS int) AS [C10],
CAST(NULL AS int) AS [C11],
CAST(NULL AS varchar(1)) AS [C12],
CAST(NULL AS varchar(1)) AS [C13],
CAST(NULL AS varchar(1)) AS [C14],
CAST(NULL AS varchar(1)) AS [C15],
CAST(NULL AS varchar(1)) AS [C16],
CAST(NULL AS varchar(1)) AS [C17],
CAST(NULL AS varchar(1)) AS [C18],
[Extent7].[MainId] AS [MainId2],
[Extent7].[Data] AS [Data],
[Extent7].[Field1] AS [Field110],
[Extent7].[Field11] AS [Field111],
[Extent7].[Field12] AS [Field121],
[Extent7].[Field14] AS [Field141],
[Extent7].[Field15] AS [Field151],
[Extent7].[Field13] AS [Field131],
[Extent7].[MainId] AS [MainId3],
CAST(NULL AS int) AS [C19],
CAST(NULL AS int) AS [C20],
CAST(NULL AS varchar(1)) AS [C21],
CAST(NULL AS varchar(1)) AS [C22],
CAST(NULL AS varchar(1)) AS [C23],
CAST(NULL AS varchar(1)) AS [C24],
CAST(NULL AS varchar(1)) AS [C25],
CAST(NULL AS varchar(1)) AS [C26],
CAST(NULL AS varchar(1)) AS [C27],
CAST(NULL AS varchar(1)) AS [C28],
CAST(NULL AS varchar(1)) AS [C29],
CAST(NULL AS int) AS [C30]
FROM (SELECT TOP (1) [Extent6].[MainId] AS [MainId], [Extent6].[Field1] AS [Field1], [Extent6].[Field11] AS [Field11], [Extent6].[Field12] AS [Field12], [Extent6].[Field13] AS [Field13], [Extent6].[Field14] AS [Field14], [Extent6].[Field15] AS [Field15], [Extent6].[Field16] AS [Field16], [Extent6].[Field17] AS [Field17], [Extent6].[Field18] AS [Field18], [Extent6].[Field19] AS [Field19]
FROM [dbo].[MainTable] AS [Extent6]
WHERE 10 = [Extent6].[MainId] ) AS [Limit3]
INNER JOIN [dbo].[MaintTable_DataLookup] AS [Extent7] ON [Limit3].[MainId] = [Extent7].[MainId]) AS [UnionAll2]
UNION ALL
SELECT
4 AS [C1],
[Limit4].[MainId] AS [MainId],
[Limit4].[MainId] AS [MainId1],
[Limit4].[Field1] AS [Field1],
[Limit4].[Field11] AS [Field11],
[Limit4].[Field12] AS [Field12],
[Limit4].[Field13] AS [Field13],
[Limit4].[Field14] AS [Field14],
[Limit4].[Field15] AS [Field15],
[Limit4].[Field16] AS [Field16],
[Limit4].[Field17] AS [Field17],
[Limit4].[Field18] AS [Field18],
[Limit4].[Field19] AS [Field19],
CAST(NULL AS int) AS [C2],
CAST(NULL AS varchar(1)) AS [C3],
CAST(NULL AS varchar(1)) AS [C4],
CAST(NULL AS varchar(1)) AS [C5],
CAST(NULL AS varchar(1)) AS [C6],
CAST(NULL AS varchar(1)) AS [C7],
CAST(NULL AS varchar(1)) AS [C8],
CAST(NULL AS varchar(1)) AS [C9],
CAST(NULL AS int) AS [C10],
CAST(NULL AS int) AS [C11],
CAST(NULL AS varchar(1)) AS [C12],
CAST(NULL AS varchar(1)) AS [C13],
CAST(NULL AS varchar(1)) AS [C14],
CAST(NULL AS varchar(1)) AS [C15],
CAST(NULL AS varchar(1)) AS [C16],
CAST(NULL AS varchar(1)) AS [C17],
CAST(NULL AS varchar(1)) AS [C18],
CAST(NULL AS int) AS [C19],
CAST(NULL AS varchar(1)) AS [C20],
CAST(NULL AS varchar(1)) AS [C21],
CAST(NULL AS varchar(1)) AS [C22],
CAST(NULL AS varchar(1)) AS [C23],
CAST(NULL AS varchar(1)) AS [C24],
CAST(NULL AS varchar(1)) AS [C25],
CAST(NULL AS varchar(1)) AS [C26],
CAST(NULL AS int) AS [C27],
[Extent9].[LookupId] AS [LookupId],
[Extent9].[MainId] AS [MainId2],
[Extent9].[MoreMoreData] AS [MoreMoreData],
[Extent9].[Field17] AS [Field171],
[Extent9].[Field16] AS [Field161],
[Extent9].[Field15] AS [Field151],
[Extent9].[Field14] AS [Field141],
[Extent9].[Field13] AS [Field131],
[Extent9].[Field12] AS [Field121],
[Extent9].[Field11] AS [Field111],
[Extent9].[Field1] AS [Field110],
[Extent9].[MainId] AS [MainId3]
FROM (SELECT TOP (1) [Extent8].[MainId] AS [MainId], [Extent8].[Field1] AS [Field1], [Extent8].[Field11] AS [Field11], [Extent8].[Field12] AS [Field12], [Extent8].[Field13] AS [Field13], [Extent8].[Field14] AS [Field14], [Extent8].[Field15] AS [Field15], [Extent8].[Field16] AS [Field16], [Extent8].[Field17] AS [Field17], [Extent8].[Field18] AS [Field18], [Extent8].[Field19] AS [Field19]
FROM [dbo].[MainTable] AS [Extent8]
WHERE 10 = [Extent8].[MainId] ) AS [Limit4]
INNER JOIN [dbo].[MainTable_EvenMoreData] AS [Extent9] ON [Limit4].[MainId] = [Extent9].[MainId]) AS [UnionAll3]
ORDER BY [UnionAll3].[C3] ASC, [UnionAll3].[C1] ASC
-- Executing at 2014-05-12 18:00:57 -04:00
-- Completed in 39 ms with result: SqlDataReader
sql server result sql server结果
why 8 rows when 2 is enough? 为什么8行时2就足够了？
this db example is not optimized with index and such but here is the execution plan 这个db示例没有使用索引进行优化等，但这里是执行计划
ideally i would like to produce a query that would look like this while keeping entity framework tracking change since i would be using the object to update the database 理想情况下，我想生成一个看起来像这样的查询， 同时保持实体框架跟踪更改，因为我将使用该对象更新数据库
SELECT dbo.MainTable.MainId, dbo.MainTable.Field1, dbo.MainTable.Field11, dbo.MainTable.Field12, dbo.MainTable.Field13, dbo.MainTable.Field14,
dbo.MainTable.Field15, dbo.MainTable.Field16, dbo.MainTable.Field17, dbo.MainTable.Field18, dbo.MainTable.Field19, dbo.MainTable_EvenMoreData.LookupId,
dbo.MainTable_EvenMoreData.MainId AS Expr1, dbo.MainTable_EvenMoreData.MoreMoreData, dbo.MainTable_EvenMoreData.Field17 AS Expr2,
dbo.MainTable_EvenMoreData.Field16 AS Expr3, dbo.MainTable_EvenMoreData.Field15 AS Expr4, dbo.MainTable_EvenMoreData.Field14 AS Expr5,
dbo.MainTable_EvenMoreData.Field13 AS Expr6, dbo.MainTable_EvenMoreData.Field12 AS Expr7, dbo.MainTable_EvenMoreData.Field11 AS Expr8,
dbo.MainTable_EvenMoreData.Field1 AS Expr9, dbo.MainTable_LookupTable.MainId AS Expr10, dbo.MainTable_LookupTable.LookupId AS Expr11,
dbo.MainTable_MoreData.DataId, dbo.MainTable_MoreData.MainId AS Expr12, dbo.MainTable_MoreData.SomeData, dbo.MainTable_MoreData.Field1 AS Expr13,
dbo.MainTable_MoreData.Field11 AS Expr14, dbo.MainTable_MoreData.Field12 AS Expr15, dbo.MainTable_MoreData.Field13 AS Expr16,
dbo.MainTable_MoreData.Field14 AS Expr17, dbo.MainTable_MoreData.Field15 AS Expr18, dbo.MaintTable_DataLookup.MainId AS Expr19,
dbo.MaintTable_DataLookup.Data, dbo.MaintTable_DataLookup.Field1 AS Expr20, dbo.MaintTable_DataLookup.Field11 AS Expr21,
dbo.MaintTable_DataLookup.Field12 AS Expr22, dbo.MaintTable_DataLookup.Field14 AS Expr23, dbo.MaintTable_DataLookup.Field15 AS Expr24,
dbo.MaintTable_DataLookup.Field13 AS Expr25
FROM dbo.MainTable LEFT OUTER JOIN
dbo.MainTable_EvenMoreData ON dbo.MainTable.MainId = dbo.MainTable_EvenMoreData.MainId LEFT OUTER JOIN
dbo.MainTable_LookupTable ON dbo.MainTable.MainId = dbo.MainTable_LookupTable.MainId LEFT OUTER JOIN
dbo.MainTable_MoreData ON dbo.MainTable.MainId = dbo.MainTable_MoreData.MainId LEFT OUTER JOIN
dbo.MaintTable_DataLookup ON dbo.MainTable.MainId = dbo.MaintTable_DataLookup.MainId
WHERE dbo.MainTable.MainId = 10
2 个解决方案
解决方案1
4 已采纳 2014-05-13 00:36:18
so after a few hours playing around, i did some load balancing / execution plan / statistic on sql server with a simple left join and the huge query that entity framework does. 所以经过几个小时的游戏，我在sql server上做了一些负载均衡/执行计划/统计，只需要一个简单的左连接和实体框架所做的巨大查询。
it seem that entity framework win by a big margin. 似乎实体框架大获全胜。
I'm going to implement the .include() solution. 我将实现.include（）解决方案。
解决方案2
2 2014-05-12 21:53:29
Yes, this is normal. 是的，这很正常。 Entity Framework is taking your (usually hierarchical) relational model and trying to produce a query that will produce all the necessary data in one big, flat table. 实体框架采用您的（通常是分层的）关系模型，并尝试生成一个查询，该查询将在一个大的平面表中生成所有必要的数据。
is it possible to keep the behavior of one include while using more than one, simple left join for all of them?
It depends on what you mean by "behavior." 这取决于你的“行为”是什么意思。 If you mean producing a similar SQL query, then no, you cannot. 如果你的意思是产生类似的SQL查询，那么不，你不能。 But one must ask why you care: these queries might be optimized for SQL Server, but they are not going to be optimized for human readability. 但是必须要问你关心的原因：这些查询可能针对SQL Server进行了优化，但它们不会针对人类可读性进行优化。
If you mean that you want to have better performance, there are strategies you can use other than eager-loading everything all in one big database round-trip. 如果您的意思是希望获得更好的性能，那么您可以使用除了在一个大型数据库往返中急切加载所有内容之外的策略。 One strategy that I've found to work well is using a new round-trip per relationship, like so: 我发现一种运作良好的策略是使用每次关系的新往返，如下所示：
var dataQuery = db.MainTables.Where(d => d.MainId == 10);
var data = dataQuery.FirstOrDefault();
dataQuery.Select(x => x.MainTable_MoreData).ToList();
// etc.
Here's a simple utility class you can use to make this less tedious, especially when loading data from several relationships deep: 这是一个简单的实用程序类，您可以使用它来减少繁琐，特别是在从多个关系深度加载数据时：
/// <summary>
/// This class aids in loading a lot of related data in Entity Framework.
/// <para>
/// Typically Entity Framework either lets you load entities Eagerly or Lazily,
/// but neither case handles things very well once you are adding many chained
/// relationships. A more ideal approach in these cases is to load all of the
/// entities you are going to need for a given relationship in a single round-trip,
/// and do this once for every relationship you're interested in.
/// That's what this class helps with.
/// </para>
/// <para>
/// To use: simply create an EntityRelationshipLoader with the initial
/// Entity-Framework-backed queryable that will be the basis of all the data
/// you're going to be loading. Then for each entity you want to load in relationship
/// to that original data type, call either <see cref="Include{TProp}"/> or
/// <see cref="IncludeMany{TProp}"/>. The return value from calling these methods may
/// be retained and used to include other property relationships based on the
/// property that you just defined. Each call to any of these methods will produce a
/// single round-trip.
/// </para>
/// <remarks>
/// Remember that all actions on the loader, including its original
/// construction, must be performed while the query's Entity Framework context
/// is active.
/// </remarks>
/// </summary>
/// <typeparam name="T"></typeparam>
public class EntityRelationshipLoader<T> : IRelationshipPropertyBuilder<T>
{
private readonly IQueryable<T> _src;
public EntityRelationshipLoader(IQueryable<T> src) : this(src, true)
{
}
private EntityRelationshipLoader(IQueryable<T> src, bool evaluateSource)
{
_src = src;
if (evaluateSource)
{
LoadEntities(src);
}
}
public IRelationshipPropertyBuilder<TProp> IncludeMany<TProp>(Expression<Func<T, IEnumerable<TProp>>> navProp)
{
LoadEntities(_src.Select(navProp));
return new EntityRelationshipLoader<TProp>(_src.SelectMany(navProp), false);
}
public IRelationshipPropertyBuilder<TProp> Include<TProp>(Expression<Func<T, TProp>> navProp)
{
return new EntityRelationshipLoader<TProp>(_src.Select(navProp), true);
}
/// <summary>
/// Simple helper method to cause the given query to be executed,
/// thereby loading all the entities the query represents.
/// </summary>
/// <param name="query"></param>
private void LoadEntities<T1>(IQueryable<T1> query)
{
#pragma warning disable 168
foreach (var item in query)
{
}
#pragma warning restore 168
}
This will allow you to say: 这将允许您说：
var dataQuery = db.MainTables.Where(d => d.MainId == 10);
var dataLoader = new EntityRelationshipLoader<MainTable>(dataQuery);
dataLoader.Include(x => x.LookupTables);
dataLoader.IncludeMany(x => x.MainTable_MoreData)
// Do you need to load MoreData's .LookupTables properties?
.Include(x => x.LookupTables);
dataLoader.Include(x => x.MaintTable_DataLookup)
dataLoader.Include(x => x.MainTable_EvenMoreData);
var data = dataQuery.Single(); // Or ToList() if you need multiple of them.
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